Compressor Digitization

[aerospacian]

i m not familiar with this terminology of over oressured,sealed pressure and under pressured etc which are labelled in the specs of transducer.info me about it.

moreover,for switching the  transducer between the pressure tubes,i have to use separate transducer for each pressure tube i think so.is there any transducer which can take 10-15 inputs (pressure tubes) and gives out signal as per the selected tube reading on the software basis or by switching.

the main critical point here which i want to discuss here is that as i need absolute (total) readings of pressure and temperature.then i think transducer selected should be absolute pressure nor differential (gage) pressure,because the reading which is coming out from the manometer when tubes were inserted in it are pressure gage and then they were added to ambient pressure (atmospheric pressure i-e 14.7psi) to get absolute pressure for performance curve.so now when i will be using transducer then the pressure tube which will be inserted in transducer will be having total pressure(absolute pressure) nor the gage pressure.what you suggest over here in this point so then i think 1 psi transducer will be rejected and i have to choose transducer of 0-16 psi range,say maximum of 20 psi.

thirdly is there any transducer which is combination of temperature and pressure sensor altogether and can give out readings for temperature and pressure input from same transducer.

thanx waiting for healthy suggestions.

[GerdW]

Hi aerospacian,

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@aerospacian wrote:

i m not familiar with this terminology of over oressured,sealed pressure and under pressured etc which are labelled in the specs of transducer.

is there any transducer which can take 10-15 inputs (pressure tubes) and gives out signal as per the selected tube reading on the software basis or by switching.

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You really should learn the basics of your measurement setup before doing any measurements. It would help to increase the reliability of your work...

For your "multi-input transducer" you could try to call Measurement Specialties...

[johnsold]

In addition to what GerdW said, you need to look at the resolution, accuracy, and hysteresis specifications of any transducers you consider.  Measuring 3 inches of water on a 1 atm base is less than 1%.  If you are not very careful, your signals will be lost in the noise.

I think you might be much better off using differential transducers with a few inches of water full scale range and a separate transducer to measure the ambient atmospheric pressure. Then calcuate the absolute pressures in software.  It is much easier to multiplex electrical signals than pressures. Connecting tubes to a manifold and using a bunch of solenoid valves to switch the pressures to a single transducer may cost more and be much more difficult to troubleshoot (leaks?), than using multiple transducers.  You could also get overpressure spikes as the solenoids switch.

Honeywell (and others) make differential pressure transducers in the pressure range you want. They sell for ~ US $50.  I have used these on several projects.  You may need to put some signal conditioning circuits close to the transducers if the environment is electrically noisy.

Lynn

[aerospacian]

please see these two files and recommend as per the whole scenario....and further DAQ card respectively according to chosen transducer...

[johnsold]

Without knowing all your specifications and the overall situation in your test setup, these recommendations should be considered tentative and preliminary.

Use one of the QP-83A devices rated at 200 or 300 kPa to measure the atmospheric pressure. If you need to measure the output pressure at various stages, use additional QP-83 devices with suitable ratings for the pressure. Use as many of the QP-86 devices as you have manometers to measure the differential pressures.  The 10 kPa model is probably the one to use, although your 3 inches of water is only about 0.75 kPa - meaning that you are only using about 10% of the full scale range of the transducer.  Since the accuracy is 0.2 to 0.5% FS, your resolution may be limited.

Depending on the distance between the transducers and the DAQ device and the ambient electrical noise, voltage or current outputs may be better.  I do not have enough information for a recommendation. Until you decide that, you cannot choose a DAQ device. The best choices will likely be different for current signals and voltage signals.

Lynn

[mikealder]

Last time I did any low pressure measurement from multiple sensors I used Huba 692 Diff Transducers configured for current output as this reduces the chances of noise on the signal cables, plenty of low pressure ranges to choose from to match to your application, for the DAQ system I used a multifunction 6052E DAQ card front ending a large SCXI rack this gave me multiple channels to display when trying to balance a complex air delivery system with multiple outlets - Mike

[aerospacian]

can u send me details of this card...either PCI,PXI etc???????? attach pdf file here plx

[aerospacian]

price of this card and transducers u referred ?????????????

[GerdW]

Hi aerospacian,

did you ever cared to follow my suggestion in this message?

[johnsold]

aerospacian,

We are trying to help you learn.  Most of the poeple who post on these Forums do so as volunteers, taking time from our other jobs.  If you want someone to do the job for you, post a description on the LabVIEW Job Openings Forum and hire someone.

Lynn